Question: Solve for $k$ : $18 + k = 23$
Answer: Subtract $18$ from both sides: $ \begin{eqnarray} \\ 18 + k &=& 23 \\ \\ {-18} && {-18} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{18 + k} &\hphantom{=}& \hphantom{23} \\ k &=& 23 {- 18} \\ \end{eqnarray} $ Simplify. $ k = 5$